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LEARNING OBJECTIVES

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  1. Interpret the findings for potential drug-induced liver damage and the presence or absence of other common hepatic disorders given the results of liver function tests.

  2. Differentiate between acute hepatocellular, obstructive, and the two types of chronic liver dysfunction using liver function tests.

  3. Differentiate drug-induced liver disease from other causes of liver pathology, using knowledge of liver function tests and other signs and symptoms.

  4. Interpret the findings for potential drug-induced renal damage, complications from chronic diseases such as hypertension and diabetes mellitus and the presence or absence of other common renal disorders given the results of renal function tests.

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INTRODUCTION

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Pharmacists in a variety of patient care practice environments are routinely required to evaluate patient’s liver function tests (LFTs) and renal function tests (RFTs) to differentiate between adverse medication effects and other causes of hepatic and renal dysfunction. The purpose of this chapter is to teach pharmacists how to evaluate patients for damage to the liver and the kidney, including those caused by complications of chronic disease, adverse drug effects, and other diseases of the liver and kidney. Pharmacists also interpret LFTs and RFTs to monitor patients taking medications with potential hepatotoxic or nephrotoxic adverse effects. Pharmacists also interpret certain RFTs to assist in the dosing of medications that are primarily excreted by the kidney.

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LIVER FUNCTION TESTS

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The term liver function tests is a misnomer, because unlike renal function tests that measure both damage to and the effectiveness of the kidney, LFTs only measure damage to various structures in the liver and gallbladder. While RFTs can be used to determine the dose of medications primarily cleared from the body via the kidney, LFTs, since they measure only damage and not function, cannot be used to determine doses of medications metabolized in the liver (Table 24.1).

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TABLE 24.1

Laboratory Tests Used to Evaluate Liver Function

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Aminotransferases

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Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are synthesized primarily in hepatocytes. Upon the destruction of hepatocytes these enzymes are released into the blood stream, causing serum levels to rise. The presence of elevated levels of AST and ALT in the serum usually indicate of hepatocellular damage. However, there are several issues that need to be considered when interpreting elevated levels ...

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